I have a 2012 passat and everytime I drive it more than just a few feet, I hear a noise coming from the rear of the car. I think its the passenger side where the DEF tank is. When I shut off the car, it is quiet for a few seconds and then there is a quiet whirring sound or quiet hum that continues for maybe 30 seconds. It almost sounds like an air pump pumping up the suspension to level the car or something. But I don't think the car has that feature. It doesn't really sound like something is wrong, but puzzles me that I don't know what it is.
Thoughts?
Thoughts?